1. Field of the Invention
The present invention relates to a hull remover by which hulls are removed from unhulled rice, and un-milled rice is retrieved, and, especially, to a couple of husking-roll driving devices with an operation (hull removing) in which hulls are peeled off from unhulled rice.
2. Description of the Related Art
The hull remover has a type by which a couple of rubber rolls are respectively rotated in the opposite directions to each other, and with different peripheral velocity from each other, un-hulled rice is supplied to a gap between the above-described couple of the rubber rolls, and shearing fracture of hulls are performed by a difference of peripheral velocities between the rollers for hull removing.
The couple of rubber rolls are a main roll, and a sub roll, but the wear of the main roll and that of the sub roll are different from each other (a deviation is caused) by a difference between the peripheral velocity of the main roll and that of the sub one. Accordingly, the wear levels are usually made the same by manual replacement operation of the rubber rolls of the main and the sub rolls. The lives of the main and sub rolls are extended by the above operations, and the above hull remover is made economically excellent.
However, the above operations by which main and sub rolls are replaced by hand are troublesome because the above operations include stopping of the hull remover and the like. Accordingly, there has been proposed a technology by which the replacement operations of the main and sub rollers can be omitted. The hull remover described in, for example, Japanese Examined Utility Model Application Publication No. 62-29064, Japanese Patent Application Laid-Open Publication No. 03-137945, and Japanese Patent Application Laid-Open Publication No. 2001-38230 has a configuration in which variable speed motors are directly connected to a main roll, and a sub one, respectively, are independently driven to be rotated from each other, and are regularly changed and switched from a high-speed side to a low-speed side, and from a low-speed side to a high-speed side. Thereby, the main and the sub rolls are equally worn because the rolls are regularly rotated in low and high speed alternately.
On the other hand, in the hull remover described in Japanese Patent Application Laid-Open Publication No. 03-106452, or Japanese Patent Application Laid-Open Publication No. 2006-312151, switching of the rotation numbers of the main and sub rolls is realized by a change gear mechanism or/and a clutch mechanism.
According to the change gear mechanism, large and small change gears fixed to a driving axis are selectively engaged with passive gears fixed to the rotation axes of the main and sub rolls. For the selective engagement, the driving axis, to which the change gears are fixed, is required to be moved in the axial direction.
The clutch mechanism uses clutch members installed onto the rotation axes of main and sub rolls. The clutch members can move in the axis directions of the rotation axes, and are restrained in the directions of the rotations, respectively. Then, there are large and small pulleys driven by a belt on the both sides of the above clutch members, and the clutch members can be selectively connected to the above pulleys. The clutch members move for rotation axes of the main and sub rolls at the same time, and, when the main roll is connected to the large pulley, the sub roll is connected to the small pulley, or vice versa. This mechanism is also required to have a configuration in which the clutch member moves along the rotation axis.
As the above devices are configured in such a way that a worn rubber roll for high speed is rotated at low speed, and a not-worn rubber roll for low speed is rotated at high speed by operating the change gear mechanism, or the clutch mechanism from the outside even in the hull removing operation by a one-touch method, the labor by which the rolls are conventionally exchanged can be omitted.
However, the hull remover described in the above-described Japanese Examined Utility Model Application Publication No. 62-29064, Japanese Patent Application Laid-Open Publication No. 03-137945, and Japanese Patent Application Laid-Open Publication No. 2001-38230 has a tendency that the remover is in overload operation because the driving motors are directly connected to the rotation axis of the low-speed side rubber roll, and that of the high-speed side one, respectively. In a word, the gap between the main and sub rubber rolls are configured to secure an appropriate contact pressure generated between the roll surface and the un-hulled rice in such a way that a predetermined husking rate (a number of un-milled rice to all numbers of added unhulled rice) is obtained. As the both rubber rolls are a viscoelastic material at this time, there is generated a maximum pressure in somewhat front side from the narrowest portion of the roll gap when the unhulled rice passes through the roll gap. The hull remover described in the Japanese Examined Utility Model Application Publication No. 62-29064, Japanese Patent Application Laid-Open Publication No. 03-137945, and Japanese Patent Application Laid-Open Publication No. 2001-38230 is required to have a large rotating driving force in order to overcome the above pressure. Accordingly, there have been a problem that the driving motors are always driven in an overload state. On the other hand, a hull remover described in Japanese Patent Application Laid-Open Publication No. 03-106452, and Japanese Patent Application Laid-Open Publication No. 2006-312151 has a merit that the repulsion forces from one couple of rolls are controlled when unhulled rice passes through the roll gap, and an excessive rotation driving force is not required to be applied to each of the driving motors because one no-end belt is wound on the pulley of the rotation axis of the high-speed side rubber roll and that of the rotation axis of the low-speed side rubber roll like cross-coupled.
However, even the hull remover described in Japanese Patent Application Laid-Open Publication No. 03-106452, or Japanese Patent Application Laid-Open Publication No. 2006-312151 has the following problems. For example, when the supplied amount of un-hulled rice is increased, a load applied to a rubber roll is increased, that is, the load on the rotation axis of a rubber roll is increased, and the axis shape of the rotation axis is changed by heat expansion and the like. Then, there has been a possibility that the switching operation becomes difficult when the gap between the main roll and the sub roll is adjusted to be made larger, or narrower, because the movements of the change gears, and that of the clutch member are in bad condition for movement in the rotation-axis direction.